1. Field of the Invention
The present invention relates to a paper container, in particular, a paper container which has a function to bind the copying papers ejected from a copying machine and stored on the tray.
2. Description of the Prior Art
As for conventional paper containers with a paper binding function which are installed on a copying machine, such devices are well known as those disclosed in U.S. Pat. Nos. 4,248,525, 4,549,804 and 3,944,207, and in Japanese patent Laid Open Publications No. 60-248563 and No. 57-72537, and in European Patent Publication No. 99250. Among these devices, the similar paper container, usually known as a finisher, has an arrangement where the copying paper undergone copying operation are stored and aligned on a tray or the like, then stapled and transferred onto a stack unit, thereby stacked and stored.
Then, some of such containers, for example, one disclosed in said European Patent Publication No. 99250 has a vane wheel-shaped paddle wheel which rotates in one specific direction in order to align a copying paper transported on a tray. In this method, however, the copying papers transported onto the tray by a transport roller readily skew, making accurate alignment difficult, because those papers are allowed to slide downward freely and reach the paddle wheel. Moreover, to accurately staple copying papers with a stapling means, the interval between supporting members on a tray requires accurate adjustment. At the same time, if a tray with a sheet aligning function is disposed in the substantially vertical direction, it is required to hold the copying papers stored on the tray while guiding the copying papers so as to prevent paper jamming.
Additionally, since any of the above mentioned paper containers is secured to a copying machine, a larger large space is required to remove jammed papers, thus resulting in a disadvantageously large apparatus. Further, such a paper container comprises an upper unit for the stapling operation and a lower stack unit which are both integrally constituted. Accordingly, there is a problem; when the upper unit is detached from the copying machine, the stack unit is at the same time detached, thereby the inertial force causes the misalignment of copying papers already having been stacked on the stack unit, and the papers to be stacked afterwards are inevitably out of alignment. Additionally, such a stack unit is designed for a user who requires a large amount of copying. Accordingly, under present circumstances, a user who only needs a small amount of copying have to use an expensive apparatus with an unnecessary powerful functions.
When the upper unit and the stack unit are independent with each other, and if either of such unit is later optionally incorporated into a copying machine, there are usually two constitutions available, as described below. First, the upper unit and the stack unit in the bottom are secured with each other, thereby the stack unit is provided with casters on the bottom surface thereof and positioned on a solid base plate. The height of base plate is designed to be adjustable. However, this arrangement causes the following problems. Since the base plate receives the load of both the upper unit and the stack unit, the height adjustment of the base plate is not necessarily each, while such a base plate incurs an increased cost. Additionally, once the adjustment has completed, it is impossible to cope with the changes in floor conditions, for example, partially depressed carpet due to the load of copying machine. In the second arrangement, the upper unit and the stack unit are completely separated and individually connected to the copying machine side. However, this arrangement also causes a problem; when another optional unit such as a sorter, paper re-feeding unit or the like is incorporated into between the copying machine and the upper unit, the stack unit hinders the incorporation.